One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(6,8)(9,10)(11,20)(12,16)(13,17)(14,18)(15,19)(21,22)(23,24)(25,26,31,34)(27,30,33,28)(29,37,38,32)(35,36,40,39)(3,7)(6,8)(11,12)(16,20)(21,23)(22,24)(25,27,31,33)(26,28,34,30)(29,35,38,40)(32,36,37,39)(1,2)(3,6)(4,5)(7,8)(9,11,15,12)(10,16,19,20)(13,21,18,23)(14,22,17,24)(25,28,31,30)(26,27,34,33)(29,36,38,39)(32,35,37,40)(1,3,4,7)(2,6,5,8)(9,12,15,11)(10,16,19,20)(13,23,18,21)(14,22,17,24)(25,29)(26,32)(27,35)(28,36)(30,39)(31,38)(33,40)(34,37)(1,2)(3,6)(4,5)(7,8)(9,13,15,18)(10,17,19,14)(11,21,12,23)(16,24,20,22)(25,26)(27,28)(29,32)(30,33)(31,34)(35,36)(37,38)(39,40)(9,14,15,17)(10,18,19,13)(11,22,12,24)(16,23,20,21)(25,30,31,28)(26,33,34,27)(29,36,38,39)(32,35,37,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.